/*
 * gre.c: gre
 *
 * Copyright (c) 2012 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <vnet/vnet.h>
#include <vnet/gre/gre.h>

gre_main_t gre_main;

typedef CLIB_PACKED (struct {
  ip4_header_t ip4;
  gre_header_t gre;
}) ip4_and_gre_header_t;

typedef struct {
  union {
    ip4_and_gre_header_t ip4_and_gre;
    u64 as_u64[3];
  };
} ip4_and_gre_union_t;


/* Packet trace structure */
typedef struct {
  /* Tunnel-id / index in tunnel vector */
  u32 tunnel_id;

  /* pkt length */
  u32 length;

  /* tunnel ip4 addresses */
  ip4_address_t src;
  ip4_address_t dst;
} gre_tx_trace_t;

u8 * format_gre_tx_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  gre_tx_trace_t * t = va_arg (*args, gre_tx_trace_t *);
    
  s = format (s, "GRE: tunnel %d len %d src %U dst %U",
              t->tunnel_id, clib_net_to_host_u16 (t->length),
              format_ip4_address, &t->src.as_u8,
              format_ip4_address, &t->dst.as_u8);
  return s;
}

u8 * format_gre_protocol (u8 * s, va_list * args)
{
  gre_protocol_t p = va_arg (*args, u32);
  gre_main_t * gm = &gre_main;
  gre_protocol_info_t * pi = gre_get_protocol_info (gm, p);

  if (pi)
    s = format (s, "%s", pi->name);
  else
    s = format (s, "0x%04x", p);

  return s;
}

u8 * format_gre_header_with_length (u8 * s, va_list * args)
{
  gre_main_t * gm = &gre_main;
  gre_header_t * h = va_arg (*args, gre_header_t *);
  u32 max_header_bytes = va_arg (*args, u32);
  gre_protocol_t p = clib_net_to_host_u16 (h->protocol);
  uword indent, header_bytes;

  header_bytes = sizeof (h[0]);
  if (max_header_bytes != 0 && header_bytes > max_header_bytes)
    return format (s, "gre header truncated");

  indent = format_get_indent (s);

  s = format (s, "GRE %U", format_gre_protocol, p);

  if (max_header_bytes != 0 && header_bytes > max_header_bytes)
    {
      gre_protocol_info_t * pi = gre_get_protocol_info (gm, p);
      vlib_node_t * node = vlib_get_node (gm->vlib_main, pi->node_index);
      if (node->format_buffer)
	s = format (s, "\n%U%U",
		    format_white_space, indent,
		    node->format_buffer, (void *) (h + 1),
		    max_header_bytes - header_bytes);
    }

  return s;
}

u8 * format_gre_header (u8 * s, va_list * args)
{
  gre_header_t * h = va_arg (*args, gre_header_t *);
  return format (s, "%U", format_gre_header_with_length, h, 0);
}

/* Returns gre protocol as an int in host byte order. */
uword
unformat_gre_protocol_host_byte_order (unformat_input_t * input,
				       va_list * args)
{
  u16 * result = va_arg (*args, u16 *);
  gre_main_t * gm = &gre_main;
  int i;

  /* Named type. */
  if (unformat_user (input, unformat_vlib_number_by_name,
		     gm->protocol_info_by_name, &i))
    {
      gre_protocol_info_t * pi = vec_elt_at_index (gm->protocol_infos, i);
      *result = pi->protocol;
      return 1;
    }

  return 0;
}

uword
unformat_gre_protocol_net_byte_order (unformat_input_t * input,
				      va_list * args)
{
  u16 * result = va_arg (*args, u16 *);
  if (! unformat_user (input, unformat_gre_protocol_host_byte_order, result))
    return 0;
  *result = clib_host_to_net_u16 ((u16) *result);
  return 1;
}

uword
unformat_gre_header (unformat_input_t * input, va_list * args)
{
  u8 ** result = va_arg (*args, u8 **);
  gre_header_t _h, * h = &_h;
  u16 p;

  if (! unformat (input, "%U",
		  unformat_gre_protocol_host_byte_order, &p))
    return 0;

  h->protocol = clib_host_to_net_u16 (p);

  /* Add header to result. */
  {
    void * p;
    u32 n_bytes = sizeof (h[0]);

    vec_add2 (*result, p, n_bytes);
    memcpy (p, h, n_bytes);
  }
  
  return 1;
}

static uword gre_set_rewrite (vnet_main_t * vnm,
			       u32 sw_if_index,
			       u32 l3_type,
			       void * dst_address,
			       void * rewrite,
			       uword max_rewrite_bytes)
{
  /*
   * Conundrum: packets from tun/tap destined for the tunnel
   * actually have this rewrite applied. Transit packets do not.
   * To make the two cases equivalent, don't generate a
   * rewrite here, build the entire header in the fast path.
   */
  return 0;

#ifdef THINGS_WORKED_AS_ONE_MIGHT_LIKE
  ip4_and_gre_header_t * h = rewrite;
  gre_protocol_t protocol;

  if (max_rewrite_bytes < sizeof (h[0]))
    return 0;

  switch (l3_type) {
#define _(a,b) case VNET_L3_PACKET_TYPE_##a: protocol = GRE_PROTOCOL_##b; break
    _ (IP4, ip4);
    _ (IP6, ip6);
#undef _
  default:
    return 0;
  }

  memset (h, 0, sizeof (*h));
  h->ip4.ip_version_and_header_length = 0x45;
  h->ip4.ttl = 64;
  h->ip4.protocol = IP_PROTOCOL_GRE;
  h->gre.protocol = clib_host_to_net_u16 (protocol);
		     
  return sizeof (h[0]);
#endif  
}

static uword
gre_interface_tx (vlib_main_t * vm,
                  vlib_node_runtime_t * node,
                  vlib_frame_t * frame)
{
  gre_main_t * gm = &gre_main;
  u32 next_index;
  u32 * from, * to_next, n_left_from, n_left_to_next;
  vnet_interface_output_runtime_t * rd = (void *) node->runtime_data;
  gre_tunnel_t *t = pool_elt_at_index (gm->tunnels, rd->dev_instance);

  /* Vector of buffer / pkt indices we're supposed to process */
  from = vlib_frame_vector_args (frame);

  /* Number of buffers / pkts */
  n_left_from = frame->n_vectors;   

  /* Speculatively send the first buffer to the last disposition we used */
  next_index = node->cached_next_index;
  
  while (n_left_from > 0)
    {
      /* set up to enqueue to our disposition with index = next_index */
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      /* 
       * As long as we have enough pkts left to process two pkts
       * and prefetch two pkts...
       */
      while (n_left_from >= 4 && n_left_to_next >= 2)
	{
          vlib_buffer_t * b0, * b1;
          ip4_header_t * ip0, * ip1;
          ip4_and_gre_union_t * h0, * h1;
	  u32 bi0, next0, bi1, next1;
	  __attribute__((unused)) u8 error0, error1;
          u16 gre_protocol0, gre_protocol1;
      
	  /* Prefetch the next iteration */
	  {
	    vlib_buffer_t * p2, * p3;

	    p2 = vlib_get_buffer (vm, from[2]);
	    p3 = vlib_get_buffer (vm, from[3]);

	    vlib_prefetch_buffer_header (p2, LOAD);
	    vlib_prefetch_buffer_header (p3, LOAD);

            /* 
             * Prefetch packet data. We expect to overwrite
             * the inbound L2 header with an ip header and a
             * gre header. Might want to prefetch the last line
             * of rewrite space as well; need profile data
             */
	    CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
	    CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
	  }

          /* Pick up the next two buffer indices */
	  bi0 = from[0];
	  bi1 = from[1];

          /* Speculatively enqueue them where we sent the last buffer */
	  to_next[0] = bi0;
	  to_next[1] = bi1;
	  from += 2;
	  to_next += 2;
	  n_left_to_next -= 2;
	  n_left_from -= 2;
      
	  b0 = vlib_get_buffer (vm, bi0);
	  b1 = vlib_get_buffer (vm, bi1);

          vnet_buffer (b0)->sw_if_index[VLIB_TX] = t->outer_fib_index;
          vnet_buffer (b1)->sw_if_index[VLIB_TX] = t->outer_fib_index;

          ip0 = vlib_buffer_get_current (b0);
          gre_protocol0 = clib_net_to_host_u16 (0x800);
          gre_protocol0 = 
              ((ip0->ip_version_and_header_length & 0xF0) == 0x60) ? 
              0x86DD : gre_protocol0;

          ip1 = vlib_buffer_get_current (b1);
          gre_protocol1 = clib_net_to_host_u16 (0x800);
          gre_protocol1 = 
              ((ip1->ip_version_and_header_length & 0xF0) == 0x60) ? 
              0x86DD : gre_protocol1;

          vlib_buffer_advance (b0, -sizeof(*h0));
          vlib_buffer_advance (b1, -sizeof(*h1));

          h0 = vlib_buffer_get_current (b0);
          h1 = vlib_buffer_get_current (b1);
          h0->as_u64[0] = 0;
          h0->as_u64[1] = 0;
          h0->as_u64[2] = 0;

          h1->as_u64[0] = 0;
          h1->as_u64[1] = 0;
          h1->as_u64[2] = 0;

          ip0 = &h0->ip4_and_gre.ip4;
          h0->ip4_and_gre.gre.protocol = gre_protocol0;
          ip0->ip_version_and_header_length = 0x45;
          ip0->ttl = 254;
          ip0->protocol = IP_PROTOCOL_GRE;

          ip1 = &h1->ip4_and_gre.ip4;
          h1->ip4_and_gre.gre.protocol = gre_protocol1;
          ip1->ip_version_and_header_length = 0x45;
          ip1->ttl = 254;
          ip1->protocol = IP_PROTOCOL_GRE;

          ip0->length = 
            clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
          ip1->length = 
            clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b1));
          ip0->src_address.as_u32 = t->tunnel_src.as_u32;
          ip1->src_address.as_u32 = t->tunnel_src.as_u32;
          ip0->dst_address.as_u32 = t->tunnel_dst.as_u32;
          ip1->dst_address.as_u32 = t->tunnel_dst.as_u32;
          ip0->checksum = ip4_header_checksum (ip0);
          ip1->checksum = ip4_header_checksum (ip1);

          /* ip4_lookup will route to the tunnel partner */
          next0 = GRE_OUTPUT_NEXT_LOOKUP;
          next1 = GRE_OUTPUT_NEXT_LOOKUP;
          error0 = GRE_ERROR_NONE;
          error1 = GRE_ERROR_NONE;

          /* 
           * Enqueue 2 pkts. This macro deals with next0 != next1,
           * acquiring enqueue rights to the indicated next
           * node input frame, etc.
           */
	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
					   to_next, n_left_to_next,
					   bi0, bi1, next0, next1);
	}

      while (n_left_from > 0 && n_left_to_next > 0)
	{
	  vlib_buffer_t * b0;
          ip4_header_t * ip0;
          ip4_and_gre_union_t * h0;
	  u32 bi0, next0;
	  __attribute__((unused)) u8 error0;
          u16 gre_protocol0;
      
	  bi0 = to_next[0] = from[0];
	  from += 1;
	  n_left_from -= 1;
	  to_next += 1;
	  n_left_to_next -= 1;
      
	  b0 = vlib_get_buffer (vm, bi0);

          vnet_buffer (b0)->sw_if_index[VLIB_TX] = t->outer_fib_index;
          ip0 = vlib_buffer_get_current (b0);
          gre_protocol0 = clib_net_to_host_u16 (0x800);
          gre_protocol0 = 
              ((ip0->ip_version_and_header_length & 0xF0) == 0x60) ? 
              0x86DD : gre_protocol0;

          vlib_buffer_advance (b0, -sizeof(*h0));

          h0 = vlib_buffer_get_current (b0);
          h0->as_u64[0] = 0;
          h0->as_u64[1] = 0;
          h0->as_u64[2] = 0;

          ip0 = &h0->ip4_and_gre.ip4;
          h0->ip4_and_gre.gre.protocol = gre_protocol0;
          ip0->ip_version_and_header_length = 0x45;
          ip0->ttl = 254;
          ip0->protocol = IP_PROTOCOL_GRE;
          ip0->length = 
            clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
          ip0->src_address.as_u32 = t->tunnel_src.as_u32;
          ip0->dst_address.as_u32 = t->tunnel_dst.as_u32;
          ip0->checksum = ip4_header_checksum (ip0);

          next0 = GRE_OUTPUT_NEXT_LOOKUP;
          error0 = GRE_ERROR_NONE;

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) 
            {
              gre_tx_trace_t *tr = vlib_add_trace (vm, node, 
                                                   b0, sizeof (*tr));
              tr->tunnel_id = t - gm->tunnels;
              tr->length = ip0->length;
              tr->src.as_u32 = ip0->src_address.as_u32;
              tr->dst.as_u32 = ip0->dst_address.as_u32;
            }

	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
					   to_next, n_left_to_next,
					   bi0, next0);
	}
  
      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  vlib_node_increment_counter (vm, gre_input_node.index,
                               GRE_ERROR_PKTS_ENCAP, frame->n_vectors);

  return frame->n_vectors;
}

static u8 * format_gre_tunnel_name (u8 * s, va_list * args)
{
  u32 dev_instance = va_arg (*args, u32);
  return format (s, "gre%d", dev_instance);
}

static u8 * format_gre_device (u8 * s, va_list * args)
{
  u32 dev_instance = va_arg (*args, u32);
  CLIB_UNUSED (int verbose) = va_arg (*args, int);

  s = format (s, "GRE tunnel: id %d\n", dev_instance);
  return s;
}

VNET_DEVICE_CLASS (gre_device_class) = {
  .name = "GRE tunnel device",
  .format_device_name = format_gre_tunnel_name,
  .format_device = format_gre_device,
  .format_tx_trace = format_gre_tx_trace,
  .tx_function = gre_interface_tx,
#ifdef SOON
  .clear counter = 0;
  .admin_up_down_function = 0;
#endif
};


VNET_HW_INTERFACE_CLASS (gre_hw_interface_class) = {
  .name = "GRE",
  .format_header = format_gre_header_with_length,
  .unformat_header = unformat_gre_header,
  .set_rewrite = gre_set_rewrite,
};

static void add_protocol (gre_main_t * gm,
			  gre_protocol_t protocol,
			  char * protocol_name)
{
  gre_protocol_info_t * pi;
  u32 i;

  vec_add2 (gm->protocol_infos, pi, 1);
  i = pi - gm->protocol_infos;

  pi->name = protocol_name;
  pi->protocol = protocol;
  pi->next_index = pi->node_index = ~0;

  hash_set (gm->protocol_info_by_protocol, protocol, i);
  hash_set_mem (gm->protocol_info_by_name, pi->name, i);
}

static clib_error_t * gre_init (vlib_main_t * vm)
{
  gre_main_t * gm = &gre_main;
  clib_error_t * error;
  ip_main_t * im = &ip_main;
  ip_protocol_info_t * pi;

  memset (gm, 0, sizeof (gm[0]));
  gm->vlib_main = vm;
  gm->vnet_main = vnet_get_main();

  if ((error = vlib_call_init_function (vm, ip_main_init)))
    return error;

  if ((error = vlib_call_init_function (vm, ip4_lookup_init)))
    return error;

  /* Set up the ip packet generator */
  pi = ip_get_protocol_info (im, IP_PROTOCOL_GRE);
  pi->format_header = format_gre_header;
  pi->unformat_pg_edit = unformat_pg_gre_header;

  gm->protocol_info_by_name = hash_create_string (0, sizeof (uword));
  gm->protocol_info_by_protocol = hash_create (0, sizeof (uword));
  gm->tunnel_by_key = hash_create (0, sizeof (uword));

#define _(n,s) add_protocol (gm, GRE_PROTOCOL_##s, #s);
  foreach_gre_protocol
#undef _

  return vlib_call_init_function (vm, gre_input_init);
}

VLIB_INIT_FUNCTION (gre_init);

gre_main_t * gre_get_main (vlib_main_t * vm)
{
  vlib_call_init_function (vm, gre_init);
  return &gre_main;
}